The phrase “public corruption” invokes images of former Illinois Governor Rod Blagojevich or disgraced Virginia Governor Robert McDonnell. Often shaped by sensational media coverage of high level officials, public perception of corruption in the United States is that it is on the rise.

But a new study that examined thousands of corruption cases from 1986 to 2014 finds that convictions are not increasing as fast as the public may think and mostly involve low-ranking officials.

The Executive Office of US Attorneys defines official corruption as criminal prosecution of public employees “for misconduct in, or misuse of office.” Examples include bribery, conspiracy, embezzlement, false statements, and theft.

“In the past, most research on public corruption relied on survey data that is of dubious quality,” says Jeffrey Milyo, professor of economics at the University of Missouri.

“In nearly all previous studies, the data used by scholars have been taken from reports made to Congress by the Public Integrity Section (PIN) of the Department of Justice. This data is compiled from retrospective surveys of federal prosecutors rather than directly from administrative records. Consequently, there are inconsistencies in reporting over time and across prosecutors in different parts of the country.”

For the study, published in the journal Public Integrity, researchers used a dataset compiled from administrative records to piece together a more accurate picture of public corruption. Electronic records of actual court case filings and up-to-date government records accessed through the Transactional Records Access Clearinghouse (TRAC), Milyo and Cordis provided a better assessment of the state of public corruption in the US.

“We examined records of more than 16,000 corruption cases from 1986 onward,” Milyo says. “This provides an objective picture of public corruption, in contrast to public perceptions that are colored by sensational media coverage of a few outlier cases. We found that overall corruption convictions are, in fact, declining from year to year and that only about 2 percent of those cases involved elected or high-ranking officials.”

Adriana Cordis, assistant professor of accounting at Winthrop University in Rock Hill, SC is a coauthor of the study.